JP6516914B2 - Mobility reference signal assignment - Google Patents

Description

  The embodiments presented herein relate to the assignment of mobility reference signals (MRS). In particular, the present invention relates to a radio access network node and method for a communication device to allocate and transmit a mobility network node reference signal to measure beam signal quality in a wireless communication network.

  In a communication network, there may be challenges to achieving good performance and capacity for a given communication protocol, its parameters and the physical environment in which the communication network is deployed.

  For example, handover is a vital part of any cellular communication network. The handover is from one radio access network node, denoted as a serving radio access network node, to another radio access network node, denoted as a target radio access network node, in order to achieve transparent service over a wide coverage area. It may be defined as the process of transferring the current connection of the wireless communication device. The handover should be performed without loss of data transmission to / from the wireless communication device and with as little interruption as possible for the wireless communication device.

  To enable handover, it is possible to discover the appropriate target cell served by the target radio access network node and maintain reliable communication to / from the radio communication device in the target cell It is necessary to make sure there is something. Suitable target radio access network nodes and / or target cell candidates are usually stored in at least the so-called neighbor list stored at the serving radio access network node. The connection quality in the target cell is estimated before handover can be performed to ensure that reliable communication to / from wireless communication devices can be maintained in the target cell It needs to be done.

  The connection quality of the target cell is generally estimated by measurements on the wireless communication device. The downlink (DL), ie transmission from the radio access network node to the radio communication device, and / or the uplink (UL), ie transmission from the radio communication device to the radio access network node may be considered. As uplink connection quality may be different from corresponding downlink connection quality, relying only on uplink measurements may be unreliable. Thus, handovers in cellular communication networks are generally based on downlink measurements.

  In existing cellular communication networks, all radio access network nodes (network nodes) continuously transmit pilot signals that wireless communication devices in neighboring cells use to estimate target cell quality. This is because such a pilot signal is transmitted on a common pilot channel (CPICH) in the global system for mobile communications (GSM (registered trademark)) in which such pilot signal is transmitted on a broadcast control channel (BCCH) In Universal Mobile Telecommunications System (UMTS), and in Long Term Evolution (LTE) telecommunication systems, where such pilot signals are transmitted as cell-specific reference signals (CRS), and such pilot signals as beacons The truth is in WiFi sent. This makes it possible to estimate the quality of neighboring cells with relatively good accuracy. The wireless communication device periodically performs the measurement and reports the measurement result to the network. If it is detected that the serving cell quality is approaching the candidate target cell quality, a more detailed measurement process or handover procedure may be initiated.

  Future cellular communication networks, such as fifth generation (5G) systems, may use antenna systems that have evolved in many aspects. With such an antenna system, signals are transmitted with narrow transmit beams to increase signal strength in one direction and / or to reduce interference in the other direction. If the antenna system is used to enhance coverage and signal quality, handovers between narrow transmit beams may be necessary to another beam in the current serving node or to beams from other candidate target network nodes. . Also, the serving network node needs to determine in its cell if beam switching or beam updating is required. The transmit beam currently in communication with the wireless communication device by the network node is called the serving beam, and the transmit beam at the handover destination or switch destination is called the target beam. The serving beam and the target beam may be transmit beams of the same or different network nodes.

  Applying the principle of continuous transmission of pilot signals in an existing cellular telecommunication network to the transmission of mobility reference signals (MRS) in all the individual transmit beams in future cellular telecommunication networks is carried out by the wireless telecommunication equipment While convenient for mobility measurements, it can degrade network performance. For example, continuous transmission of MRS in all individual transmit beams may cause a large amount of interference in the network due to the presence of many narrow transmit beams, which otherwise consumes available network capacity for data It can also increase the power consumption of the network.

  Furthermore, in communication networks that rely on evolved antennas with narrow transmit beams to improve coverage, it is inefficient, and in some cases even impossible, to simultaneously transmit MRS on all transmit beams. The usual option of transmitting continuously in different beams leads to longer measurement periods and slower handovers and beam updates.

  The network also makes handover decisions based on mobility measurement reports sent by the wireless communication device. The quality and accuracy of the measurement results largely depend on the MRS allocation. For example, to obtain a sufficient measurement signal to noise ratio in a wireless communication device, a sufficient number of MRS resource elements (REs) must be available for each measurement. As another example, in an MRS deployment with short span REs, the measurement results may be overly affected by instantaneous fading.

  Accordingly, there is a need for an improved network node and method for assignment and transmission of measurement reference signals in future communication networks for mobility measurements performed by wireless communication devices.

  The purpose of the embodiments herein is to provide an improved method and network node in a wireless communication network for assignment and transmission of measurement reference signals enabling wireless communication devices to perform mobility measurements efficiently and with high accuracy. To provide.

  According to a first aspect of an embodiment herein, the object is a network node for a wireless communication device to allocate and transmit a mobility reference signal (MRS) to measure beam signal quality in a wireless communication network. This is achieved by the method implemented in The network node first obtains information on one or more of frequency diversity of a channel between the network node and the wireless communication device, time diversity, and antenna space diversity of the wireless communication device. Then, the network node selects an MRS pattern from the set of candidate patterns based on the received information. Furthermore, the network node signals the selected MRS pattern to the wireless communication device and transmits the MRS according to the selected MRS pattern.

  According to a second aspect of the embodiments herein, the object is a network node for a wireless communication device to allocate and transmit a mobility reference signal (MRS) to measure beam signal quality in a wireless communication network. Achieved by The network node is configured to obtain information of one or more of frequency diversity of a channel between the network node and the wireless communication device, time diversity, antenna space diversity of the wireless communication device. The network node further selects an MRS pattern from the set of candidate patterns based on the received information, signals the selected MRS pattern to the wireless communication device, and transmits the MRS according to the selected MRS pattern Configured to

  By transmitting the MRS according to the selected MRS pattern, the beam signal quality report by the wireless communication device reflects the average beam quality in most scenarios and conditions. As a result, the determination of beam switching is robust and the number of switching over time is minimized. This is accomplished without over-dimensioning the MRS allocation for all wireless communication devices in all situations. For existing systems, these advantages are enabled by dedicated, i.e. wireless communication device specific, DL mobility reference signaling, activation and transmission.

  In another aspect, there is provided a computer program comprising instructions that, when executed on at least one processor in a network node, cause the network node to perform the method according to the aspect summarized above.

  In another aspect there is provided a carrier comprising a computer program according to the above summarized aspect, wherein the carrier is any of an electronic signal, an optical signal, a wireless signal and a computer readable storage medium.

  These other aspects provide the same effects and advantages as the method aspects summarized above.

Examples of embodiments herein will now be described in more detail with reference to the accompanying drawings.
FIG. 7 is a schematic diagram illustrating an example of a DL-MRS structure. FIG. 1 is a schematic diagram illustrating a wireless communication network according to embodiments herein. Figure 5 is a flow chart of a method performed in a network node according to embodiments herein; FIG. 5 is a schematic diagram illustrating an example of a MRS pattern. FIG. 5 is a block diagram illustrating functional modules of a radio access network node according to embodiments herein.

  As part of developing the embodiments herein, the handover or beam switching procedure and the DL-MRS, first submitted as a patent application by the applicant of the present application and proposed to a standardization group for future new communication systems Describe the structure and identify and discuss some relevant issues.

  As used herein, the term "wireless communication device" refers to a user terminal (UE), a subscriber unit, a mobile telephone, a mobile phone, a personal digital assistant (PDA) with wireless communication capabilities, a smart phone, internal or external It may refer to a laptop or personal computer (PC) with a mobile broadband modem, a tablet PC with wireless communication capabilities, a portable electronic wireless communication device, etc.

  Furthermore, as used herein, the term "MRS" refers to one MRS symbol per field, "MRS pattern" refers to a set of MRS symbols for one beam and one mobility session, "DL- “MRS” refers to time synchronization signal (TSS) or MRS in one mobility subframe for one beam, “DL-MRS structure” refers to TSS / MRS in one mobility subframe for all candidate beams Point to.

Beam Switching Procedure: As mentioned in the background, continuous transmission of MRS on all separate transmit beams is not efficient. It will be appreciated that for most of the time, only a few beams may need to be active as reasonable candidate target beams. In order to avoid always-on mobility reference signals, the network instead turns on the appropriate set of candidate target beams as the need for serving beam updates arises. For example, the serving network node may detect when the current downlink serving beam has begun to degrade by considering channel quality reports received from wireless communication devices, eg, based on information in a look-up table (LUT). A downlink based mobility measurement session may be triggered if the quality falls below a threshold. The mobility measurement session includes activating transmission of a mobility reference signal (DL-MRS) in the downlink for the set of candidate target beams and requesting the wireless communication device to perform the measurement. The wireless communication device then performs measurements on the candidate target beam and reports the results to the network. Additional signaling may occur, for example, the network may inform the wireless communication device about the subset of beams to look for and which reference symbols or beam signature sequences to use.

  After receiving the mobility measurement report of the wireless communication device, the network is informed about a suitable target beam and beam switching is performed. In a preferred network deployment, beam switching is performed in a manner also referred to as UE-unaware mode, which is transparent to the wireless communication device or user terminal (UE). The new serving beam identity, direction, origin node etc are not explicitly signaled to the UE. All active mode control and data traffic continue with the established UE identity, eg, Radio Network Temporary Identifier (RNTI) configuration. The transmit DL beam parameters may be changed on an SF basis, as long as the UE makes no consistent assumption of channel and interference over subframes (SF).

Beam Mobility Reference Signal Structure: In each beam, the DL-MRS performs the following functions:
Time and frequency synchronization on the beam, even if transmitted from another node not closely synchronized with the serving node;
Beam signature detection and identification where there are other beams activated simultaneously;
• Signal elements necessary to achieve beam signal quality measurements to evaluate received beam power or signal to interference and noise ratio (SINR), preferably reflecting average quality and not instantaneous quality for fast fading It is included and included.

  An example of a DL-MRS design is shown in FIG. The upper diagram shows a DL-MRS region, which includes a time synchronization signal (TSS) field and an MRS field, each having six physical resource blocks (PRBs). For example, if the physical resource block consists of 12 subcarriers in frequency and 7 orthogonal frequency division multiplexed (OFDM) symbols in time, the 6 PRB wide DL-MRS regions in frequency have 72 subcarriers. The middle figure shows how DL-MRS area is arranged in one SF, where physical downlink shared channel (PDSCH) area and control channel (CCH) area are shown. There is. The lower diagram shows a 10 ms frame with multiple SFs, where SFs including DL-MRS regions are marked. The TSS field allows coarse time and frequency synchronization in the time domain, which is similar to the primary synchronization signal (PSS) in LTE systems. The MRS field contains beam-specific signature sequences used for measurements in the frequency domain by correlating beam identification and reference signature sequences, which is similar to the secondary synchronization signal (SSS) in LTE systems. The same type of adjacent fields are used for time multiplexed signals from different beams. Furthermore, the DL-MRSs of different beams may be code-multiplexed by using the nearly orthogonal characteristics of the MRS sequences. In this design, each field occupies the middle six Physical Resource Blocks (PRBs) in the transmitted band. The mobility report of the UE is configured to reflect one or more DL-MRS qualities measured for the beam. The DL-MRS is available with a period of 5 ms in this example, but the DL-MRS is activated only when the UE is present.

  In order to minimize the number of beam switches over time, the UE needs to report an MRS measurement report, which averages the average beam signal quality for fast fading. The network sets the structure of the DL-MRS and the rate of the DL-MRS SF according to criteria that result in good average performance for the network. However, depending on the propagation scenario, the selected DL-MRS setting may serve to average the instantaneous fading better or relatively less. Thus, in some cases, the reported UE measurements may be dependent on the instantaneous variation experienced in a given portion of the time-frequency plane.

  Thus, according to embodiments herein, a design of DL-MRS is provided that can provide consistent beam quality estimates in all encountered scenarios. The DL-MRS in the candidate beam for the UE is configured to provide sufficient diversity to obtain an averaged measurement result during one mobility measurement session. A method for the setup of the MRS will now be more fully described with reference to the accompanying drawings.

  FIG. 2 is a schematic diagram illustrating a communication network 200 to which the embodiments presented herein are applicable. The communication network 200 comprises radio access network nodes 211, 212, 213. The network node may be a combination of base stations, Node Bs, and / or radio base stations such as evolved Node Bs. The network nodes may further be any combination of macro network nodes 211, 212 and micro or pico network nodes 213. Each network node 211, 212, 213 transmits network beams 251, 252, 253, 254, 255, 256 in its coverage area 221, 222, 223 so that network coverage in the respective coverage area 221, 222, 223 I will provide a. Each network node 211, 212, 213 is assumed to be operatively connected to a core network (not shown). And, the core network may be operatively connected to the service and data provision wide area network.

  Thus, wireless communication devices 241, 242 serviced by any of the network nodes 211, 212, 213 may thereby access the services and data provided by the wide area network. The wireless communication devices 241, 242 can be any combination of mobile stations, mobile phones, handsets, wireless local loop phones, UEs, smart phones, laptop computers, and / or tablet computers.

  The wireless communication devices 241, 242 move from one location to another and thus from the coverage areas 221, 222, 223 and thus from one network node to another or at least one transmit beam A handover of the wireless communication device 241, 242 from one to another transmit beam may be required. As mentioned above, such a handover should be performed without losing data transmission to / from the wireless communication device and with as little interruption as possible for the wireless communication device. The serving beam and the target beam may be transmit beams of the same or different network nodes. Thus, the term handover as used herein should be interpreted as a handover from a source beam to a target beam.

  Here, an example of an embodiment of a method implemented in the network nodes 211, 212, 213 for allocating and transmitting an MRS for the wireless communication devices 241, 242 to measure beam signal quality in the wireless communication network 200. Will be described with reference to FIG. The method includes the following operations, which may be performed in any suitable order.

Operation 301
In order to provide sufficient diversity to obtain averaged measurement results during one mobility measurement session, the network nodes 211, 212, 213 have knowledge of the channel conditions between the network nodes and the communication equipment. Need to have. Thus, the network node 211, 212, 213 obtains one or more pieces of information of frequency diversity of the channel between the network node and the wireless communication device, time diversity, antenna space diversity of the communication device.

  The frequency diversity of a channel can refer to the coherence bandwidth of the channel due to the dispersion of the channel, denoted for example as Cf. The coherence bandwidth is the bandwidth at which the channel response may be assumed to be relatively flat. The coherence bandwidth is related to the inverse of the delay spread. The shorter the delay spread, the larger the coherence bandwidth. The delay spread is an amount of multipath richness of the communication channel. In general, delay spread can be interpreted as the difference between the arrival time of the earliest large multipath element, typically a line of sight (LOS) element, and the arrival time of the latest multipath element.

  In a communication system, the communication channel may change with time. The coherence time is a time interval in which the channel impulse response is considered to be relatively unchanged. Such channel variations are very noticeable in wireless communication systems due to the Doppler effect. Thus, time diversity of a channel can refer to channel spread by Doppler spread or vehicle velocity, denoted, for example, as Ct.

  The network nodes 211, 212, 213 may obtain estimates of the channel dispersion metric or coherence bandwidth Cf and the Doppler metric or channel coherence time Ct from UL measurements for the communication device. Instead, the communication device may estimate them in the DL and report them to the network node in the UL.

  Antenna space diversity of a wireless communication device can refer to, for example, the correlation between the number of antenna elements and the antenna elements of the wireless communication device. A communications device may report its antenna diversity characteristics, eg, the number of receive antennas denoted A, and / or antenna array structure, antenna correlation, etc. as part of its capability signaling. The signals from several receive antennas can be correlated. The network node may estimate the effective number of independent antennas, denoted Ai, for the communication device based on its capabilities and correlation information, current channel information, etc.

Operation 302
The network nodes 211, 212, 213 select MRS patterns from among the set of candidate patterns based on the received information.

Broadly, if one or more of the time, frequency diversity factors are low, the following MRS configuration criteria may be taken to increase the available diversity:
Assign MRS PRBs or resource elements (REs) over a wider frequency span or more densely in frequency if the inherent frequency diversity is large.
Allow measurement over more mobility SF periods during one session, if the inherent time diversity is large, or increase the density of mobility SF grids in time.

  Based on these principles, an appropriate MRS pattern is selected based on the acquired information from among several possible patterns that provide a predetermined number of measurements that fade at least independently. The selection is preferably made to minimize the total number of reference symbols per measurement session under the constraints of one or more time and frequency domain assignments.

  An example of selection criteria and processing for setting up the MRS pattern will be described in detail with reference to FIG.

  FIG. 4 shows an example of an MRS pattern, where the vertical axis represents the frequency dimension in units of subcarriers, eg, the vertical axis comprises 12 subcarriers and the horizontal axis is a symbol of eg It represents the time dimension in units of OFDM symbols. As shown in FIG. 4, the MRS pattern includes Nf number of subcarriers in the frequency dimension, eg, Nf = 4, which is spaced by a distance Df in units of subcarriers, eg, Df = 3 For example, it includes Nt symbols in the time dimension with an interval Dt in units of OFDM symbols, ie, Nt = 4, Dt = 5 during one mobility measurement session. One mobility measurement session may include several SFs, and in this example, one mobility measurement session covers 1.5 SFs. One SF may include 14 OFDM symbols or 2 resource blocks (RBs), and in the case of an LTE system or the like, each RB includes 7 OFDM symbols. Alternatively, the frequency allocation may be Nf PRBs with a spacing Df in units of 12 subcarriers.

  Here, the units for the frequency in the subcarrier and the time in the symbol are merely examples, and one skilled in the art will realize that other units may be available, for example, the frequency in the PRB and the unit of time in the subframe. It should.

  Let Ct be the channel coherence time in the number of OFDM symbols and let Cf be the channel coherence bandwidth in the number of subcarriers. Then, in this example, Ct = 4.2 and Cf = 2.5.

  The total number of antennas in the communication device is A, and the number of independent antennas is Ai.

  The main purpose of the proposed adaptive DL-MRS setup process is to allow the communication device to base its mobility measurement on a sufficient number of measurement symbols to fade independently, ie to REs in multiple MRS fields. It is to guarantee. The minimum acceptable number of independent measurement symbols is represented by Mmin. In one embodiment, Mmin is a predetermined number of independent measurement symbols and may be assigned as Mmin = 10.

  In order to guarantee a sufficient measured SINR, the total number of measured symbols has to be larger than normal, the limit is represented by Lmin, for example, Lmin can be set as 50.

  The total number L of symbols to be measured is determined as L = A * Nt * Nf by the number of antennas A in the wireless communication device, the number of subcarriers Nf in the frequency dimension, and the number Nt of symbols in the time dimension. Therefore, the total number of measurement symbols L should be equal to or greater than Lmin, that is, L ≧ Lmin.

Based on coherence time and bandwidth considerations, the MRS patterns in a given time-frequency span have at most Nf * Df / Cf in the frequency dimension and at most Nt * Dt / Ct independent symbols in the time dimension. Can be provided. The total number of independent measurement symbols, denoted M, is therefore
M = Ai * ceil (Nt * [min (1, Dt / Ct)]) * ceil (Nf * [min (1, Df / Cf)])
It is.

  Here, the functions min (1, Dt / Ct) and min (1, Df / Cf) are for determining how "independent" the symbols are. Dt and Df are, for example, Dt> Ct and Df> Cf so that the symbols are independent, such that min (1, Dt / Ct) = 1, min (1, Df / Cf) = 1 Properly selected. Alternatively, they may be smaller than Ct and Cf to establish that Lmin is satisfied. The function ceil (x) returns the smallest integer greater than or equal to x.

  Therefore, the number M of independent measurement symbols in the total number L of measurement symbols is the number of independent antennas Ai in the wireless communication device, the number Nf of subcarriers, the ratio of the interval Df in the frequency dimension to the coherence bandwidth Cf, ie Df It is determined by / Cf, the number of symbols Nt, and the ratio of the interval Dt in the time dimension to the channel coherence time Ct, that is, Dt / Ct.

  According to some embodiments, the network nodes 211, 212, 213 first include different numbers Nf of subcarriers with different intervals Df in the frequency dimension and different numbers Nt of symbols with different intervals Dt in the time dimension. The number M of independent measurement symbols is evaluated for different sets of candidate patterns having.

  The network node then determines the number of resource elements in the frequency and time dimensions, ie Nf *, based on the maximum frequency span limit (Fmax), the maximum mobility measurement session length limit (Tmax) and the minimum number Lmin of measurement symbols. Nt selects the smallest MRS pattern.

In other words, the network node evaluates different sets of parameters Nf, Df, Nt, Dt such that L = A * Nf * Nt ≧ Lmin, where a sufficient total number of measurement symbols are received. For each such set Nf, Df, Nt, Dt, evaluate the number M of effective independent measurement symbols, and the following conditions and constraints:
M M Mmin
Nf * Df ≦ Fmax
Nt * Dt ≦ Tmax
Choose the set in which Nf * Nt is minimized with.

  Here, Fmax is the limit of the largest frequency span. The maximum frequency span limitation may be related to the allowed frequency range of DL-MRS signaling or the total bandwidth of the carrier, eg, in FIG. 4 Fmax may be 12 subcarriers.

  Tmax is the maximum mobility session length limit. Tmax may relate to the expected time before the communication device loses synchronization on the current serving beam. The limitation is that for communication devices with high Doppler spread, or, for example, in areas of the network where it is known that sudden beam loss will occur by losing beam coverage when moving around corners Can be reduced for the telecommunication equipment of

  According to some embodiments, during one mobility measurement session, the number Nf * Nt of resource elements in the frequency and time dimensions is minimized. As mentioned above, one mobility measurement session may include several SFs. If more than one SF is used, the MRS symbols should be spread to have the same Dt.

  In the embodiment described above, the selection process is to evaluate a group of predetermined MRS patterns. According to another embodiment, multi-dimensional numerical optimization algorithms may be applied using more flexible parameter settings. For example, optimization of the MRS pattern may be pre-computed for a limited set of possible input parameters, and then selection of the MRS pattern maps the input parameters to an index to perform a table lookup Done by

  The MRS pattern shown in FIG. 4 is merely an example, and more flexible setting according to FIG. 4 is possible.

  According to some embodiments, simpler MRS assignment principles may be used. In one embodiment, each MRS pattern may have a predetermined number of subframes per second, and the number of SFs per mobility measurement session is increased to compensate for small channel dispersion and / or small Doppler. Ru. This may be viewed as an application of the general method described above with a set of candidate parameter sets limited to varying a single parameter.

  In some scenarios, fast fading may be very or extremely slow and may not need to be averaged in mobility measurement reporting. This may be the case for lines of sight (LOS) that can be detected by the network node and channels dominated by Rice, for example by direction of arrival (DOA) detection or channel estimation analysis from the antenna array of the network node. If the analysis detects a single dominant wavefront, a minimal set of MRS can be configured for mobility measurement.

Operation 303
After setting or selecting the MRS pattern, the network node signals the selected MRS pattern to the wireless communication device. The communication device then knows at which frequency and when to receive the MRS.

Operation 304
After the network node notifies the communication device of the selected MRS pattern, the network node transmits the MRS according to the selected MRS pattern.

  The above operations are performed for one MRS sequence transmitted in one beam, but the procedure may be applied in all beams, and MRS can be allocated and transmitted in all candidate beams, That is, more REs can be reserved for MRS transmission given by the MRS pattern for one beam. The DL-MRS structure may be fixed or the DL-MRS structure may be provided by the MRS pattern.

  Usually, the diversity provided by the propagation channel is determined by the scattering around the communication device and the movement of the communication device, and thus is similar for all serving and candidate beams. Thus, the diversity parameters estimated from the serving beam may also be used to assign DL-MRS to candidate beams. In certain scenarios, eg, very high Doppler, which may vary for different network nodes, the network may set assignments for communication devices according to worst case assumptions.

  The proposed configurations and procedures are adaptive and can handle special cases such as near-zero channel dispersion, eg negligible frequency fading, or quasi-static operation, eg negligible time fading, diversity Other available dimensions can be used effectively to generate.

  By transmitting the MRS according to the selected MRS pattern, the beam signal quality report by the communication device reflects the average beam quality in most scenarios and conditions. As a result, the beam switching decision is robust and the number of switches over time is minimized. This is achieved without overdimensioning the MRS allocation for all communication devices in all situations. Unlike existing systems, these advantages are enabled by dedicated, ie, communication device specific, DL mobility reference signal configuration, activation and transmission.

  For example, the MRS may be selected and activated in a candidate beam set including a serving beam and / or a possible target beam, and the communication devices 241, 242 may be instructed to perform measurements on that MRS. The measurement results may then be reported to the network nodes 211, 212, 213 and appropriate beam switching or cell handover operations may be performed.

  In order to carry out the method in the network nodes 211, 212, 213 described in connection with FIG. 3, the communication devices 241, 242 allocate and transmit MRS to measure beam signal quality in the wireless communication network 200 The network nodes 211, 212, 213 have the following circuits or modules illustrated in FIG. The network nodes 211, 212, 213 may include, for example, a receiving module 510, a transmitting module 520, and a determining module 530.

  The network nodes 211, 212, 213 use, for example, the receiver module 510 configured as described above, for channel frequency diversity, time diversity, wireless, between the network nodes 211, 212, 213 and the wireless communication devices 241, 242. It is configured to obtain information about one or more of the antenna space diversity of the communication device 241, 242.

  The network nodes 211, 212, 213 are further configured to select an MRS pattern from the set of candidate patterns based on the received information, for example using the so configured determination module 530.

  The network nodes 211, 212, 213 further signal the selected MRS pattern to the radio communication equipment 241, 242, for example using the so configured transmission module 520, and MRS according to the selected MRS pattern Configured to send

  According to some embodiments, information about one or more of frequency diversity, time diversity, and antenna space diversity may include channel dispersion or channel coherence bandwidth, channel Doppler spread or channel coherence time, number of antenna elements, and The antenna element correlation of the wireless communication devices 241 and 242 is included.

  Furthermore, the definitions of the parameters Nf, Nt, Ct, Cf, L, Lmin, M, Mmin, Fmax, Tmax are similar to those described in connection with the operation of the method.

  According to some embodiments, the network nodes 211, 212, 213 further include different subcarrier numbers Nf and time dimensions with different spacing Df in the frequency dimension, eg using the determination module 530 so configured Evaluate the number of independent measurement symbols M for different sets of candidate patterns with different number of symbols Nt with different spacing Dt in and limit the maximum frequency span Fmax, the maximum mobility measurement session length limit Tmax, and Based on the minimum number Lmin of symbols, it is configured to select the MRS pattern with the minimum number of resource elements in the frequency and time dimensions.

  Those skilled in the art will appreciate that the receiving module 510, the transmitting module 520, the determining module 530 described above may be configured with one module, a combination of analog and digital circuitry, software and / or firmware such as the processor 540 shown in FIG. It will be understood that it may refer to one or more processors and / or other digital hardware that performs the function of each module. Whether individually packaged or assembled on a system-on-chip (SoC), one or more of these processors, a combination of analog and digital circuitry, and other digital hardware, have a single specific application It may be included in a directed integrated circuit (ASIC), or several processors and various analog / digital hardware may be distributed among several separate components.

  The network nodes 211, 212, 213 may further include a memory 550 that includes one or more memory units. The memory 550 may, for example, information such as beam signatures and identification information, a list of target beams, measurement results and data, and settings for performing the method herein when performed in the network nodes 211, 212, 213. It is adapted to be used for storage.

  The embodiments herein at the network nodes 211, 212, 213 where the communication devices 241, 242 allocate and transmit MRS to measure beam signal quality in the wireless communication system 200 perform the functions and operations of the embodiments herein. May be implemented through one or more processors, such as the processor 540 at the network node 211, 212, 213 with the computer program 541. The computer program described above may be provided as a computer program product, for example in the form of a data carrier 542 carrying a computer program for performing the embodiments herein when deployed on network nodes 211, 212, 213. One such carrier may be in the form of a CD ROM disc. However, this can be implemented using other data carriers, such as a memory stick. The computer program may be provided as pure program code on a server and downloaded to the network nodes 211, 212, 213.

  When using the terms "comprise" or "comprise", it must be interpreted in a non-limiting manner, meaning "consist at least of."

  The embodiments herein are not limited to the preferred embodiments described above. Various alternatives, modifications and equivalents may be used. Accordingly, the above embodiments should not be taken as limiting the scope of the invention, which is defined by the appended claims.

Claims (22)

A method implemented in a network node (211, 212, 213) in which a wireless communication device (241, 242) allocates and transmits a mobility reference signal (MRS) to measure beam signal quality in a wireless communication network (200) There,
About one or more of frequency diversity of the channel between the network node (211, 212, 213) and the wireless communication device (241, 242), time diversity, antenna space diversity of the wireless communication device (241, 242) To obtain the information of (301),
Selecting 302 an MRS pattern from the set of candidate patterns based on the received information;
Signaling (303) the selected MRS pattern to the wireless communication device (241, 242);
Transmitting 304 the MRS according to the selected MRS pattern;
Only including,
Selecting (302) an MRS pattern from the set of candidate patterns based on the received information comprises:
Independent measurement symbols for different sets of candidate patterns with different subcarrier numbers (Nf) with different intervals (Df) in frequency dimension and different symbol numbers (Nt) with different intervals (Dt) in time dimension Evaluating the number (M),
Number of resource elements in frequency and time dimensions based on one or more of maximum frequency span limit (Fmax), maximum mobility measurement session length limit (Tmax), and minimum number of measurement symbols (Lmin) Selecting the smallest MRS pattern,
Wherein the free Mukoto a.   The information about one or more of frequency diversity, time diversity, and antenna space diversity may be channel dispersion or coherence bandwidth of the channel, Doppler spread or channel coherence time of the channel, the wireless communication device (241, 242). The method according to claim 1, wherein the number of antenna elements and the antenna element correlation are included.   The method of claim 1, wherein each MRS pattern has a predetermined number of subframes per second.   Each MRS pattern has the number of subcarriers (Nf) with an interval (Df) in the frequency dimension and the number of symbols (Nt) with an interval (Dt) in the time dimension during one mobility measurement session, The method according to claim 1, characterized in that The total number (L) of measurement symbols is determined by the number of antennas (A) in the wireless communication device (120), the number of subcarriers in the frequency dimension ( Nf ) and the number of symbols in the time dimension ( Nt ) The method according to claim 4, characterized in that: Wherein the number of independent measurements symbol of the total number of measurement symbol (L) (M) is the number of independent antenna in the communication device (241,242) (Ai), the number of subcarriers (Nf), Frequency Defined by the ratio of the spacing ( Df ) to the channel coherence bandwidth ( Cf ) , the number of symbols ( Nt ) , the ratio of the spacing ( Dt ) to the channel coherence time ( Ct ) in the time dimension, The method according to claim 5, characterized in that Wherein selecting the MRS pattern, the maximum frequency span limit (Fmax), the maximum mobility measurement session length limit (Tmax), and the minimum number of measurement symbols (Lmin) in rather based, wherein the this The method according to any one of claims 1 to 6, wherein Method according to claim 7, characterized in that the number ( M ) of independent measurement symbols is greater than a predetermined number ( Mmin ) of independent measurement symbols.   The method of claim 7, wherein the number of resource elements in frequency and time dimensions is minimized during one mobility measurement session.   The method according to claim 9, characterized in that one measurement session comprises a plurality of subframes. A network node (211, 212, 213) to which a wireless communication device (241, 242) allocates and transmits a mobility reference signal (MRS) to measure beam signal quality in a wireless communication network (200),
About one or more of frequency diversity of the channel between the network node (211, 212, 213) and the wireless communication device (241, 242), time diversity, antenna space diversity of the wireless communication device (241, 242) Get the information of
Selecting an MRS pattern from the set of candidate patterns based on the received information;
Signaling the selected MRS pattern to the wireless communication device (241, 242);
Transmitting the MRS according to the selected MRS pattern,
And so on ,
Independent measurement symbols for different sets of candidate patterns with different subcarrier numbers (Nf) with different intervals (Df) in frequency dimension and different symbol numbers (Nt) with different intervals (Dt) in time dimension Evaluate the number (M),
Number of resource elements in frequency and time dimensions based on one or more of maximum frequency span limit (Fmax), maximum mobility measurement session length limit (Tmax), and minimum number of measurement symbols (Lmin) Selects the smallest MRS pattern,
Network node, wherein the configured (211, 212, 213).   The information about one or more of frequency diversity, time diversity, and antenna space diversity may be channel dispersion or coherence bandwidth of the channel, Doppler spread or channel coherence time of the channel, antenna of the communication device (241, 242) The network node (211, 212, 213) according to claim 11, characterized in that it comprises the number of elements and the antenna element correlation.   The network node (211, 212, 213) according to claim 11, characterized in that each MRS pattern has a predetermined number of subframes per second. Each MRS pattern has a number of subcarriers ( Nf ) with an interval ( Df ) in the frequency dimension and a number of symbols ( Nt ) with an interval ( Dt ) in the time dimension during one mobility measurement session, Network node (211, 212, 213) according to claim 11, characterized in that The total number (L) of measurement symbols is determined by the number of antennas (A) in the wireless communication device (120), the number of subcarriers in the frequency dimension ( Nf ) and the number of symbols in the time dimension ( Nt ) Network node (211, 212, 213) according to claim 14, characterized in that: Wherein the number of independent measurements symbol of the total number of measurement symbol (L) (M) is the number of independent antenna in a wireless communication device (241,242) (Ai), the number of the subcarriers (Nf), It is defined by the ratio of the interval ( Df ) to the channel coherence bandwidth ( Cf ) in the frequency dimension, the number of symbols ( Nt ) , the ratio of the interval ( Dt ) in the time dimension to the channel coherence time ( Ct ) , Network node (211, 212, 213) according to claim 15, characterized in that. The MRS pattern, the maximum frequency span limit (Fmax), the maximum mobility measurement session length limit (Tmax), and are selected based on the minimum number of measurement symbols (Lmin), and wherein the this The network node (211, 212, 213) according to any one of claims 11 to 16. Network node (211, 212, 213) according to claim 17, characterized in that said number ( M ) of independent measurement symbols is greater than a predetermined number ( Mmin ) of independent measurement symbols.   The network node (211, 212, 213) according to claim 17, characterized in that the number of resource elements in frequency and time dimensions is minimized during one mobility measurement session.   The network node (211, 212, 213) according to claim 19, characterized in that one measurement session comprises a plurality of subframes.   A computer comprising instructions which, when executed in at least one processor (540) in a network node (211, 212, 213), cause said network node to carry out the method according to any one of claims 1-10. Program (541). A computer readable storage medium storing the computer program according to claim 21.

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